The results obtained from RCT treatments have been improved due to recent breakthroughs in surgical techniques and the development of new surgical instruments. However, failure rates reach 40% when it comes to massive injuries [9]. Actually, some authors report that up to 30% of all RCTs can be classified as irreparable, given their dimension associated with the severe muscle degeneration [10, 11].
Painful and dysfunctional shoulders in active working individuals with irreparable injuries in the rotator cuff (RC) are a major challenge. Reverse shoulder arthroplasty (RSA) is a valuable option in chronic treatments; nevertheless, in young active arthrosis-free patients, the limited lifespan of RSA and the considerable potential for complex revisions after the event of infections or instability are great concerns [12–15].
Muscle transfers for these injuries are a feasible alternative with promising results, and the most vastly studied transfer is the great dorsal to the tuberosity [16]. However, the results are not reproducible or constant [17, 18], so other options have been tried and assessed, and today the literature encourages the use of the LT in muscle transfers, especially in the treatment of brachial plexus paralysis and massive rotator cuff tears. Biomechanical evidences show that LT transfers are more anatomical than those of the latissimus dorsi (LD) with better outcomes for abduction, flexion and external rotation [19, 20].
According to Burkhart [21], in order to establish the balance in the glenohumeral articulation for any arm position, there must be a balance between force and moment. Biomechanical studies reveal that LT transfer is more effective in the restoration of this balance [22].
For the past few years, there have been many descriptions of different techniques for lower trapezius transfer, particularly in regard to the type of graft used in its fixation in the greater tuberosity of the humerus. Valenti et al.[7] used only the folded semitendinosus tendon with an extension band of 20 cm attached to humeral head in two different ways: the first with cortical button (Zip Tight®) and the second with anchors. There is no reference in the literature regarding the right placement of the graft insertion.
Some studies on the biomechanics of shoulder muscle transfers are available in the literature. Omid et al. [22] measured the forces applied to the humeral head during rotations, at neutral and humeral head apex positions in shoulders with rotator cuff injury and compared LT and LD transfers. The authors observed that the LT transfer was more effective when it came to restoring values closer to those of an intact rotator cuff. Reddy et al. [20] measured muscular tension in 3 different positions of the arm comparing LT and LD transfers: (1) supraspinatus footprint; (2) infraspinatus footprint; and (3) the teres minor footprint. However, no anatomical relation between the width of the graft and the insertion area to be occupied could be found in the literature. On the other hand, some anatomical articles show that the insertion area of the infraspinatus occupies 20 mm of width in the greater tuberosity [8] which theoretically shows the importance of having a graft that is compatible with this size.
The technique here described searches for a better placement for the reinsertion of the semitendinosus and gracilis graft for the original footprint of the IS tendon in the greater tuberosity of the humerus. The graft is wider, and it is able to cover all the insertion of the IS in the greater tuberosity of the humerus, as shown by Mochizuki et al [8].
Whenever a tendon is submitted to constant elongation and remains at the same length for longer periods, the corresponding force will progressively decrease [23]. This phenomenon is known as static force relaxation. This is the reason why the tendons associated with the semitendinosus were used here so that their resistance could be increased.
Theoretically, this technique offers two advantages. The first one is anatomical due to the capacity of a better coverage of the native footprint; the second is the creation of a more physiological vector and the improvement of the biomechanical resistance. Nevertheless, these advantages should be more thoroughly investigated in future studies.